People gather at a makeshift memorial for victims near the site of the Boston Marathon bombings at the edge of a closed section of Boylston Street a day after the second suspect was captured on April 20, 2013 in Boston, Massachusetts. (Photo by Mario Tama/Getty Images)

(CNN) – Fifteen days after the Boston Marathon bombings, Massachusetts voters head to the polls Tuesday to select Democratic and Republican nominees in a special U.S. Senate election that's been almost completely overshadowed by the terror attacks.

Even before the bombings, Massachusetts voters weren't paying that much attention to the contest to fill the remaining year and a half of the term of longtime Democratic Sen. John Kerry, who stepped down earlier this year to become U.S. secretary of state.FULL POST

Federal agents are looking into possible links between dead Boston Marathon bomb suspect Tamerlan Tsarnaev and a Canadian boxer-turned-jihadist killed by Russian troops in 2012, a source being briefed on the investigation said Monday. William Plotnikov and six others died in a firefight with Russian forces in the southwestern republic of Dagestan in July 2012, while Tsarnaev was visiting the region, the source said. The 23-year-old Plotnikov was born in Russia, but his family moved to Canada when he was a teenager. The source said Plotnikov's body was prepared for burial by a local imam on July 14. Tsarnaev flew out of Dagestan two days later, arriving in New York on July 17. Investigators are looking into the possibility he left because of Plotnikov's death, the source said.

WATCH: VIDEO – Sources tell CNN that female DNA has been found on the bomb in the Boston attack. Susan Candiotti reports.

(CNN) - As the debate between Elizabeth Colbert Busch and former South Carolina Gov. Mark Sanford got under way Monday, there was an elephant in the room: Would Colbert Busch mention Sanford’s infamous extramarital affair?

About halfway into the showdown, the Democratic candidate vying to represent the state’s 1st Congressional District took a swipe at the Republican and his secret 2009 trip to see his mistress in Argentina.FULL POST

CNN's GUT CHECK | for April 29, 2013 | 5 p.m.
– n. a pause to assess the state, progress or condition of the political news cycle

DEVELOPING: Pentagon steps up planning for potential military intervention in Syria… “There is intensified planning in the works as more precise information comes in on the Syrian regime's potential use of chemical weapons and the body of evidence grows,” a senior administration official said. The official, who has direct knowledge of the effort, declined to be identified because of the sensitivity of the situation. If President Barack Obama were to order action, it could involve thousands of U.S. troops. But all of the options face serious military challenges. – Barbara Starr

FROM CONVENTION HOST TO TRANSPORTATION HEAD: President Barack Obama tapped Charlotte Mayor Anthony Foxx on Monday to head the Transportation Department. If confirmed by the Senate, Foxx would replace Ray LaHood. – Kevin Liptak

(CNN) - Jack Hoffman, the 7-year-old who famously scored a touchdown during the Nebraska Cornhuskers spring game earlier this month, visited the White House Monday and had a chat with the president in the Oval Office.

Star running back Rex Burkhead befriended the young football fan and brain cancer patient last year. Burkhead helped create a play on the field in which Hoffman could run a 69-yard touchdown.

(CNN) – They've been going after each other from a distance. Now they get to do it in person.

Monday evening former South Carolina Gov. Mark Sanford and Elizabeth Colbert Busch debate for the first time in their battle for the Palmetto State's vacant congressional seat, in an entertaining race that's grabbed national attention.FULL POST

Washington (CNN) – President Barack Obama tapped the mayor of Charlotte, North Carolina on Monday to head his Department of Transportation.

If confirmed by the Senate, Foxx would replace Ray LaHood, who said in January he wouldn't serve a second term. LaHood has said he will remain in his post until a successor is confirmed. The transportation secretary is responsible for overseeing the nation's roads, airports and railways.FULL POST